Evaluation of a torque converter clutch position based on accumulated slip

Patent metadata

Field	Value
Publication number	US-10697539-B2
Application number	US-201815969076-A
Country	US
Kind code	B2
Filing date	May 2, 2018
Priority date	May 2, 2018
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A system for determining a torque converter clutch is stuck in an engaged position includes a control module, an engine speed sensor, and a transmission speed sensor. The control module evaluates the torque converter clutch by determining a value of a torque converter clutch command. The torque converter clutch command indicates a position of the torque converter clutch. In response to determining that the value of the torque converter clutch command indicates the disengaged position, the control module calculates accumulated slip based on the transmission speed and the engine speed during an evaluation time. In response to determining the evaluation time is complete, the control module compares the accumulated slip with a calibrated threshold of slip. In response to the accumulated slip being less than or equal to the calibrated threshold of slip, the control module determines the torque converter clutch is stuck in the engaged position.

First claim

The following is claimed:

1. A system for a transmission of a motor vehicle, the transmission including a torque converter having a torque converter clutch configured to actuate between an engaged position and a disengaged position, the system comprising:
a transmission speed sensor configured to monitor a rotational speed of a transmission input shaft that represents a transmission speed;
an engine speed sensor configured to monitor a rotational speed of a crankshaft that represents an engine speed; and
a control module in electric communication with the transmission speed sensor and the engine speed sensor, the control module configured to:
determine a value of a torque converter clutch command, wherein the torque converter clutch command indicates a position of the torque converter clutch;
in response to determining that the value of the torque converter clutch command indicates the disengaged position, calculate accumulated slip based on the transmission speed and the engine speed during an evaluation time;
in response to determining the evaluation time is complete, compare the accumulated slip with a calibrated threshold of slip;
in response to the accumulated slip being less than or equal to the calibrated threshold of slip, determine the torque converter clutch is stuck in the engaged position; and
in response to determining the torque converter clutch is stuck in the engaged position, determine at least one mitigating action.

2. The system of claim 1 , further comprising:
a vehicle speed sensor in electronic communication with the control module, wherein the vehicle speed sensor indicates vehicle speed.

3. The system of claim 2 , further comprising:
a throttle position sensor configured to monitor the position of a throttle body, wherein the throttle position sensor is in communication with the control module.

4. The system of claim 3 , further comprising:
a transmission fluid temperature sensor in communication with the control module, wherein the transmission fluid temperature sensor is configured to monitor a fluid temperature of the transmission.

5. The system of claim 4 , wherein the control module is further configured to evaluate the torque converter clutch by:
determining the transmission fluid temperature is greater than a threshold temperature;
in response to determining the transmission fluid temperature is greater than the threshold temperature, monitoring the vehicle speed and the throttle body position;
determining a clutch apply speed based on the vehicle speed and the throttle body position, wherein the clutch apply speed represents a threshold vehicle speed at which the torque converter clutch is instructed to actuate into the engaged position for a given throttle position; and
in response to determining the vehicle speed is less than or equal to the clutch apply speed, setting the value of the torque converter clutch command to the disengaged position.

6. The system of claim 1 , further comprising:
a transmission range sensor in electric communication with the control module, wherein the transmission range sensor is configured to send a transmission range value to the control module indicating a position of a selector lever.

7. The system of claim 6 , wherein the evaluation time and the calibrated threshold of slip are based on the position of the selector lever.

8. The system of claim 1 , wherein the control module determines the accumulated slip based on:
Accumulated Slip=Σ 0 Evaluation Time ( N engine −N turbine )

wherein N engine is the rotational speed of the crankshaft and N turbine is the rotational speed of the transmission input shaft.

9. The system of claim 1 , wherein the control module determines an average error offset based on:

Average
⁢

⁢
Error
⁢

⁢
Offset

=

⁢

∑
0

Evaluation
⁢

⁢
Time

⁢

(

N
engine

-

N
Turbine

)

Evaluation
⁢

⁢
Time

wherein N engine is the rotational speed of the crankshaft and N turbine is the rotational speed of the transmission input shaft.

10. The system of claim 9 , wherein the control module determines a corrected value for the accumulated slip based on:
Corrected Slip=Σ 0 Evaluation Time ( N engine −N turbine −Average Error Offset)

wherein corrected slip is the correct value of the accumulated slip.

11. The system of claim 1 , wherein the control module includes a counter, and wherein the counter is incremented in response to determining the accumulated slip is less than or equal to the calibrated threshold of slip.

12. The system of claim 11 , wherein the control module determines the torque converter clutch is stuck in the engaged position based on a value of the counter being equal to or greater than a threshold number of failed evaluations.

13. A method of determining a torque converter clutch of a transmission is stuck in an engaged position, the method comprising:
monitoring, by a computer, a transmission speed sensor for transmission speed that represents a rotational speed of a transmission input shaft;
monitoring, by the computer, an engine speed sensor for an engine speed that represents a rotational speed of a crankshaft;
determining, by the computer, a value of a torque converter clutch command, wherein the torque converter clutch command indicates a position of the torque converter clutch;
in response to determining that the value of the torque converter clutch command indicates a disengaged position, calculating accumulated slip based on the transmission speed and the engine speed during an evaluation time;
in response to determining the evaluation time is complete, comparing the accumulated slip with a calibrated threshold of slip;
in response to the accumulated slip being less than or equal to the calibrated threshold of slip, determining the torque converter clutch is stuck in the engaged position; and
in response to determining the torque converter clutch is stuck in the engaged position, determining at least one mitigating action.

14. The method of claim 13 , further comprising:
monitoring, by the computer, a vehicle speed sensor, wherein the vehicle speed sensor indicates vehicle speed.

15. The method of claim 14 , further comprising:
monitoring, by the computer, a throttle position sensor that indicates a throttle body positi

Assignees

• Gm Global Tech Operations Llc

Inventors

• Moorman Steven P

Classifications

• F16D2500/3067

  Speed of the engine · CPC title

• F16D2500/3108

  Vehicle speed · CPC title

• F16D2500/1045

  Friction clutch · CPC title

• F16D2500/30406

  Clutch slip · CPC title

• F16H2342/00

  Calibrating · CPC title